1. Field of the Invention
The present invention is related to a circuit board and a method of manufacturing the same, and particularly to a circuit board having an odd number of circuit layers and a manufacturing method thereof.
2. Description of Related Art
As the electronic technology advances rapidly and the high-technology electronic industry continues burgeoning in recent years, electronic products with more human touch and better functions keep hitting the market and developing towards the trend of light weight, slimness, and tiny and compact size. Inside these electronic products are usually disposed circuit boards having conductive circuits.
For those conventional circuit boards, the manufacturing method thereof usually includes forming a first conductive layer at both sides of a core layer. Afterwards, each of the first conductive layers is patterned to form a first circuit layer. Then, two dielectric layers and two second conductive layers are laminated respectively at the both sides of the core layer by lamination so that the dielectric layers are laminated between the core layer and the second conductive layer. Next, openings are formed in the second conductive layer and the dielectric layers respectively to expose the first circuit layers. Then, an copper electroplating process is performed to form a conductive via in each of the openings. Thereafter, each of the second conductive layers is patterned to form a second circuit layer on the dielectric layer, and the second circuit layers are connected to the first circuit layers through the conductive vias. Certainly, more circuit layers may be formed in the same way to fulfill actual requirements.
Since circuit layers are sequentially formed at the both sides of the core layer symmetrically, the circuit board thus manufactured has an even number of circuit layers. However, the aforementioned manufacturing method often limits the scope of freedom for circuit design, which means that circuit boards to be thereby manufactured must have an even number of circuit layers. In addition, some circuit boards do not require using an even number of circuit layers. Therefore, the said manufacturing method often results in redundant circuit layers in the circuit boards and thereby causes waste in manufacturing costs.